Have you tried working with an addictions counselor or a dual diagnosis therapist?
I am in no way making a moral equivocation between them, but the way this fixation upsets you and messes with your stability reminds me a lot of people who have other taboo compulsions - pain, underage people, things like that. I had people with those issues in my family. Most of them describe those compulsions as having been present from their earliest memories. I wonder if therapists especially trained in those issues might have insight that would be useful to you.